Transmissible venereal tumor (TVT) or Sticker tumor is a naturally occurring horizontally transmitted round cell tumor in dogs. It commonly affects the external genitalia and is usually transmitted at coitus. Other sites of occurrence include the nasal and oral cavity, and rarely subcutaneous areas. The tumor has been reported to occur in most parts of the world but appears to be more prevalent in temperate climates or in areas with large population of stray dogs. It is seen most often in young, roaming, sexually intact and active dogs. A viral etiology has been investigated but not verified. The TVT may also involve extragenital sites, and this may occur due to auto transplantation. This may be the way in which TVTs develop in the oral cavity, nasal cavity, the skin, the sclera, and the anterior chamber. TVT can be transmitted to young puppies by subcutaneous inoculation. Immunocompromised dogs are also more prone to metastatic lesions. They are usually cauliflower like in appearance, friable, and red to flesh colored. Hemorrhage is a common problem. The definitive diagnosis is based on either a histologic or cytologic evaluation of the tumor. Thoracic radiographs are invariably negative for metastasis. Surgical excision alone there tends to be a high recurrence rate (20-60%) and can be effective for small localized nodules. TVT is one neoplastic process that can be readily cured with chemotherapy. A number of agents have been used, these include, vincristine, cyclophosphamide, doxorubicin, and possibly methotrexate. Vincristine has been reported to be one of the most effective agents in treating TVT. This study describes a case of a primary ocular TVT in a mixed-breed dog. It was a four-month old intact male dog and was treated at Veterinary Hospital--UNESP--Botucatu. It had a nodule in the superior palpebral conjunctiva with 2 cm in diameter. The animal had been found on the street by its owner a month before, having the nodule already, which showed a slow, but progressive growth. Fine needle aspirates taken from the nodule were examined cytologically and cytological findings were consistent with the diagnosis of TVT. No primary tumor was detected in the genital area or in the oral or nasal cavity, making metastatic dissemination unlikely. Four treatments were carried out with Vincristine at a dose of 0.75mg/m² intravenous once a week and induced a complete remission. No toxicity was noted.